Method of making an indirect bonding tray for orthodontic treatment

ABSTRACT

An indirect bonding tray for use in applying and bonding orthodontic appliances to a patient&#39;s teeth is made by providing a replica of the patient&#39;s dentition including replicas of the patient&#39;s teeth. A guide is provided on each replica tooth in a location corresponding to the ultimate intended location of the orthodontic appliance on the patient&#39;s teeth. Each guide has a receptacle for receiving an orthodontic appliance, and serves to ensure that the respective orthodontic appliance is placed in its proper, intended position on the replica tooth. A tray is then formed over the replica teeth and the appliances for subsequent use in bonding the appliances to the patient&#39;s teeth.

BACKGROUND OF THE INVENTION

1. Field of the Invention

This invention relates to an indirect bonding tray that is used forplacing orthodontic appliances on the surfaces of a patient's teeth.More particularly, the present invention is directed toward a method andan assembly for making an indirect bonding tray.

2. Description of the Related Art

Orthodontic treatment involves movement of malpositioned teeth todesired locations in the oral cavity. Orthodontic treatment can improvethe patient's facial appearance, especially in instances where the teethare noticeably crooked or where the jaws are out of alignment with eachother. Orthodontic treatment can also enhance the function of the teethby providing better occlusion during mastication.

One common type of orthodontic treatment involves the use of tiny,slotted appliances known as brackets. The brackets are fixed to thepatient's teeth and an archwire is placed in the slot of each bracket.The archwire forms a track to guide movement of teeth to desiredlocations.

The ends of orthodontic archwires are often connected to smallappliances known as buccal tubes that are, in turn, secured to thepatient's molar teeth. In many instances, a set of brackets, buccaltubes and an archwire is provided for each of the patient's upper andlower dental arches. The brackets, buccal tubes and archwires arecommonly referred to collectively as “braces”.

In many types of orthodontic techniques, the precise position of theappliances on the teeth is an important factor for helping to ensurethat the teeth move to their intended final positions. For example, onecommon type of orthodontic treatment technique is known as the“straight-wire” technique, where the archwire lies in a horizontal planeat the conclusion of treatment. Consequently, if a bracket is attachedto the tooth at a location that is too close to the occlusal or outertip of the tooth, the orthodontist using a straight-wire technique willlikely find that the tooth in its final position is unduly intruded. Onthe other hand, if the bracket is attached to the tooth at a locationcloser to the gingiva than is appropriate, it is likely that the finalposition of the tooth will be more extruded than desired.

In general, orthodontic appliances that are adapted to be adhesivelybonded to the patient's teeth are placed and connected to the teeth byeither one of two techniques: a direct bonding technique, or an indirectbonding technique. In the direct bonding technique, the appliance andadhesive are grasped with a pair of tweezers or other hand instrumentand placed by the practitioner on the surface of the tooth in anapproximate desired location. Next, the appliance is shifted along thesurface of the tooth as needed until the practitioner is satisfied withits position. Once the appliance is in its precise, intended location,the appliance is pressed firmly onto the tooth to seat the appliance inthe adhesive. Excess adhesive in areas adjacent the base of theappliance is removed, and the adhesive is then allowed to cure and fixthe appliance firmly in place.

While the direct bonding technique described above is in widespread useand is considered satisfactory by many, there are shortcomings that areinherent with this technique. For example, access to surfaces ofmalposed teeth may be difficult. In some instances, and particularly inconnection with posterior teeth, the practitioner may have difficultyseeing the precise position of the bracket relative to the toothsurface. Additionally, the appliance may be unintentionally dislodgedfrom its intended location during the time that the excess adhesive isbeing removed adjacent the base of the appliance.

Another problem associated with the direct bonding technique describedabove concerns the significant length of time needed to carry out theprocedure of bonding each appliance to each individual tooth. Typically,the practitioner will attempt to ensure that each appliance ispositioned in its precise, intended location before the adhesive iscured, and some amount of time may be necessary before the practitioneris satisfied with the location of each appliance. At the same time,however, the patient may experience discomfort during the procedure andhave difficulty in remaining relatively motionless, especially if thepatient is an adolescent. As can be appreciated, there are aspects ofthe direct bonding technique that can be considered a nuisance for boththe practitioner and for the patient.

Indirect bonding techniques avoid many of the problems noted above. Ingeneral, indirect bonding techniques known in the past have involved theuse of a placement device or transfer tray having wall sections with ashape that matches the configuration of at least part of the patient'sdental arch. Often, the tray has a generally “U”-shaped channel forreceiving a number of teeth simultaneously. A set of appliances such asbrackets are releasably connected to the tray at certain, predeterminedlocations within the channel.

During the use of orthodontic transfer tray for indirect bonding, anadhesive is typically applied to the base of each appliance by theorthodontist or a staff member. The tray is then placed over thepatient's teeth and remains in place until such time as the adhesivehardens. Next, the apparatus is detached from the teeth as well as fromthe appliances, with the result that all of the appliances previouslyconnected to the tray are now bonded to respective teeth at theirintended, predetermined locations.

In more detail, one method of indirect bonding of orthodontic appliancesusing the transfer tray described above includes the steps of taking animpression of each of the patient's dental arches and then making areplica plaster or “stone” model from each impression. Next, theappliances are bonded to the stone models at desired locations.Optionally, the bonding adhesive can be a chemical curing adhesive (suchas Concise brand adhesive from 3M) or a light-curable adhesive (such asTransbond XT brand adhesive or Transbond LR brand adhesive from 3M).Optionally, the brackets may be adhesive precoated brackets such asthose described in U.S. Pat. Nos. 5,015,180, 5,172,809, 5,354,199 and5,429,299.

The transfer tray is then made by placing a matrix material over themodel as well as over the appliances placed in the model. For example, aplastic sheet matrix material may be held by a frame and exposed toradiant heat. Once the plastic sheet material has softened, it is placedover the model and the appliances. Air in the space between the sheetmaterial and the model is then evacuated, and the plastic sheet materialassumes a configuration that precisely matches the shape of the replicateeth of the stone model and attached appliances.

The plastic sheet matrix material is then allowed to cool and harden toform a tray. The tray and the appliances (which are embedded in aninterior wall of the tray) are then detached from the stone model. Ifthe cured adhesive that was used to bond the appliances to the stonemodel remains on the base of the appliances after detachment from thestone model, the adhesive serves as a “custom” base having a concavecontour that precisely replicates the convex contour of the previousattachment location of the stone model, as well as the convexconfiguration of the intended mounting location of the appliances on thepatient's teeth.

Once the patient has returned to the practitioner's office, a quantityof adhesive is placed on the base of each appliance, and the tray withthe embedded appliances is then placed over the matching portions of thepatient's dental arch. Since the configuration of the interior of thetray closely matches the respective portions of the patient's dentalarch, each appliance is ultimately positioned on the patient's teeth atprecisely the same location that corresponds to the previous location ofthe same appliance on the stone model.

In recent years, many improvements have been made in the field ofindirect bonding. For example, U.S. Pat. No. 5,971,754 describes atwo-component indirect bonding adhesive with a relatively fast curingtime that reduces the length of time that the tray must be firmly heldagainst the patient's teeth. U.S. Pat. No. 6,123,544 describes atransfer tray that receives movable arms for placing appliances on thepatient's teeth once the tray is positioned in the oral cavity.Published U.S. Patent Application entitled “METHOD AND APPARATUS FORINDIRECT BONDING OF ORTHODONTIC APPLIANCES” (U.S. Publication No.2004-0219471, published on Nov. 4, 2004), describes among other things atransfer apparatus with an improved matrix material for releasablyholding appliances in place. Pending U.S. Patent Application entitled“APPARATUS FOR INDIRECT BONDING OF ORTHODONTIC APPLIANCES AND METHOD OFMAKING THE SAME” (U.S. Ser. No. 10/678,286, filed on Oct. 3, 2003)describes among other things a transfer apparatus that includes at leastone appliance having a base with a contour that is a replica of acontour of a portions of the patient's tooth structure, and a bondingcomposition on the base for bonding to the patient's tooth structure.

Indirect bonding techniques offer a number of advantages over directbonding techniques. For one thing, and as indicated above, it ispossible to bond a plurality of appliances to a patient's dental archsimultaneously, thereby avoiding the need to bond each appliance inindividual fashion. In addition, the transfer apparatus helps to locatethe appliances in their proper, intended positions such that adjustmentof each appliance on the surface of the tooth before bonding is avoided.The increased placement accuracy of the appliances that is oftenafforded by indirect bonding techniques helps ensure that the patient'steeth are moved to their proper, intended positions at the conclusion oftreatment.

However, the ultimate location of the appliances on the patient's teethduring an indirect bonding procedure is determined by the earlier,temporary location of the appliances on the replica teeth. Consequently,it is important to ensure that the appliances are precisely placed onthe replica teeth at the correct, pre-determined locations. Theabove-mentioned U.S. Pat. No. 5,971,754 describes a method of markingthe replica teeth with a pencil using a gauge to determine the locationof the pencil mark, and the appliances are subsequently aligned by eyeto the pencil mark and then visually checked to ensure accurateplacement.

As alternative to manual placement of appliances, a computer controlledrobotic arm may be used to grasp each appliance in sequence and place iton the associated tooth. For example, if the replica dental arch is madeusing digital information, a computer may be used to calculate anidealized position for each appliance on the patient's tooth, and thatinformation can then be used in a set of instructions to controlmovement of the robotic arm such that the appliance is placed on thecorresponding, selected location of the associated replica tooth. Withthis method, the use of pencil marks for visual alignment of theappliances may be avoided.

However, the use of a robotic arm to place appliances on replica teethpresents difficulties in the manufacturing process of making the trays.For example, there are a vast number of different orthodonticappliances, each having a unique shape and prescription, and theparticular appliance selected will often vary from tooth to tooth, frompatient to patient, and from practitioner to practitioner. Consequently,it would be a somewhat expensive task to set up an automated system forfeeding the appliances to the robotic arm due to the large number ofavailable appliances that may be needed for any particular patient.Moreover, it may be difficult to construct a set of universal jaws forthe robotic arm in order to pick up each appliance, as the externalshape of the various appliances may greatly differ.

SUMMARY OF THE INVENTION

The present invention is directed toward improved methods and assembliesfor making an indirect bonding tray. A replica of the patient'sdentition is provided, as well as a set of guides that extend over toothstructure of the replica. Each guide has a receptacle for receiving anorthodontic appliance such that the appliance is positioned over thereplica tooth structure at a precise, pre-determined location.

Preferably, the guides have a shape that is at least partiallycomplemental to the base of the appliance to be received in the guide.As a result, the practitioner can simply select the correct appliancefrom an inventory of appliances, and then place the appliance in thereceptacle. The guide helps to position the appliance in its precise,intended location on the replica tooth. As a result, the use of manualpositioning techniques or an automated robotic arm can be avoided.

In more detail, the present invention is directed in one aspect to amethod of making an indirect bonding tray for orthodontic treatment. Themethod comprises:

providing a replica of a patient's dentition, wherein the replicaincludes replica tooth structure;

providing a guide on the replica tooth structure at a locationcorresponding to the intended location of an orthodontic appliance onthe patient's tooth structure;

placing an orthodontic appliance on the replica tooth structure next tothe guide; and

forming a tray over the replica including the orthodontic appliance.

The present invention in another aspect is directed toward an assemblyfor making an indirect bonding tray for orthodontic treatment. Theassembly comprises a dentition replica including a number of replicateeth, and a number of guides each connected to a corresponding tooth ofthe dentition replica. Each of the guides includes a receptacle. Theassembly further includes a number of orthodontic appliances eachreceived in a corresponding receptacle.

Additional aspects of the present invention are described in theparagraphs that follow and are illustrated in the accompanying drawings.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a top and front view showing a physical replica of one dentalarch of an orthodontic patient, illustrating an example of a replica ofa patient's tooth structure and adjacent gingival tissue as they mightappear before the commencement of treatment, and additionally showing anumber of placement guides extending over teeth of the replica;

FIG. 2 is a view somewhat similar to FIG. 1 of the replica and theplacement guides, and additionally illustrating a number of appliancesthat have been received in respective receptacles of the placementguides;

FIG. 3 is a fragmentary, enlarged front elevational view looking in alingual direction toward one of the appliances, placement guides andreplica teeth shown in FIG. 2;

FIG. 4 is a fragmentary enlarged side view in partial section, takenalong lines 4-4 of FIG. 3;

FIG. 5 is a view somewhat similar to FIG. 4 except that the placementguide has been removed from the replica tooth and a sheet of spacermaterial has been applied to the appliance and the replica tooth;

FIG. 6 is a view somewhat similar to FIG. 5, additionally showing ashell that has been formed over the spacer material;

FIG. 7 is a view of the dentition replica shown in FIG. 1 after thespacer material and the shell have been detached from the replica, andadditionally showing three stop members that have been placed alongocclusal sections of the replica teeth;

FIG. 8 is an enlarged side cross-sectional view of one of the replicateeth and one of the appliances after the placement guide has beenremoved, and additionally showing a transfer tray that comprises theouter shell and a matrix material located between the shell and thereplica;

FIG. 9 is an enlarged side cross-sectional view illustrating the act ofapplying the transfer tray to one of the patient's teeth; and

FIG. 10 is a view somewhat similar to FIG. 4 except showing a placementguide constructed in accordance with an alternate embodiment of theinvention;

DEFINITIONS

“Mesial” means in a direction toward the center of the patient's curveddental arch.

“Distal” means in a direction away from the center of the patient'scurved dental arch.

“Occlusal” means in a direction toward the outer tips of the patient'steeth.

“Gingival” means in a direction toward the patient's gums or gingiva.

“Facial” means in a direction toward the patient's cheeks or lips.

“Lingual” means in a direction toward the patient's tongue.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

A replica of a portion of a dental arch of an orthodontic patient isdesignated broadly by the numeral 20 in FIG. 1. For exemplary purposes,the replica 20 represents the patient's lower dental arch. However, areplica of a patient's upper dental arch may also be provided as anaddition to or as an alternative to the lower dental arch replica 20 asshown. As a further option, the replica 20 may represent only a portionof the dental arch, such as a quadrant of an arch or only one or twoteeth of a dental arch.

In the example illustrated, the replica 20 includes a number of replicateeth 22, each corresponding to one of the teeth of the patient's lowerdental arch. In addition, the replica 20 includes replica gingivaltissue 24. However, the replica gingival tissue 24 is optional, and maybe provided only to an extent needed to securely hold the replica teeth22 together.

A number of placement guides 26 extend over the dentition replica 20. Inthe example illustrated in FIG. 1, ten placement guides 26 are provided,each associated with one of ten of the replica teeth 22. Each of theplacement guides 26 includes a central receptacle 28 disposed over thesurface of the corresponding replica tooth 22.

FIG. 2 is an illustration somewhat similar to FIG. 1 except showing anumber of appliances 30 that have each been received in a correspondingone of the receptacles 28. FIG. 3 is an enlarged front view of one ofthe appliances 30, one of the placement guides 26 and one of the replicateeth 22 depicted in FIG. 2. FIG. 4 is another enlarged illustration ofthe same appliance 30, receptacle 28 and replica tooth 22 except thisview is looking in a distal direction and is in partial cross-sectionalview.

Preferably, each receptacle 28 has an inner perimeter or wall surfacethat is complemental in configuration to at least a portion of the baseof the appliance 30 that is received in that receptacle 28. For example,and as shown in the drawings, the base of the appliance 30 may includefour sides, namely a mesial side, a gingival side, a distal side and anocclusal side. The four sides of the base of the appliance 30 may bestraight or generally straight and resemble a rectangle or square in afrontal view, or alternatively may be smoothly curved to form a somewhatcircular, oval-shaped or tooth-shaped configuration in facial view.

In the embodiment illustrated, the placement guide 26 includes a mesialwall section 32, a gingival wall section 34 and a distal wall section36, and the sections 32, 34, 36 are integrally connected together. Thethree sections 32, 34, 36 define the receptacle 28 and are positioned toclosely engage the mesial side, the gingival side and the distal siderespectively of the base of the appliance 30. As a consequence, when theappliance 30 is received in the receptacle 28, movement of the appliance30 relative to the placement guide 26 is substantially prohibited inmesial, gingival and distal directions.

Alternatively, the placement guide 26 may have other constructions aswell. For example, the mesial wall section 32 and the distal wallsection 36 may extend along the mesial-occlusal corner and thedistal-occlusal corner respectively of the appliance base. As anotherexample, the placement guide 26 may include four sections including anocclusal section in addition to the mesial, gingival and distalsections. Preferably, this occlusal section does not extend continuouslyalong the occlusal side of the appliance base and instead includes a gapor space to permit the passage of the extruded composition (such asadhesive) as is further explained below.

As yet another alternative, the wall sections of the placement guide 26may comprise a series of spaced apart sections, posts or other types ofprotrusions that define a receptacle. However, it is preferred that theplacement guides 26 have sufficient structure to receive thecorresponding appliance 30 in the receptacle 28 with little, if anyspace between the inner wall surfaces of the placement guide 26 and theappliance 30. To this end, the receptacles 28 may vary in shape from onereceptacle to the next as may be needed to matingly receive applianceshaving bases with different configurations.

Preferably, the height of the wall sections 32, 34, 36 in a facialdirection is limited so that excess composition that is extruded frombeneath the base of the appliance 30 is not directed toward certainareas of the appliance 30, such as areas beneath tiewings or areasdefining an archwire slot. An example of a suitable height in a facialdirection is approximately 0.5 mm greater than the thickness of theappliance base in directions along a facial-lingual reference axis.

In the embodiment shown in FIGS. 1-4, the placement guides 26 are madeby applying a material to the replica 20, either after the replica 20has been formed or as the replica 20 is formed. As one option, a rapidprototyping machine (such as a Stratasys Dimension SST (Soluble SupportTechnology) from Stratasys, Inc. of Eden Prairie, Minn.) can be used toform the replica 20 as well as the various placement guides 26. First,digital data is obtained that is representative of the patient's teethand adjacent gingival tissue. The digital data may be obtained by theuse of a hand-held intra-oral scanner or other device known in the art.As another option, the digital data may be obtained by scanning animpression of the patient's teeth or a physical model (e.g., a modelmade of epoxy or plaster of Paris) of the patient's teeth. The digitaldata is then used in computer software associated with the rapidprototyping machine to make the dentition replica 20.

Preferably, the computer software also includes subprograms suitable toanalyze the existing malocclusion of the patient and assist indetermining the desired ultimate positions of the appliances 30 on thepatient's teeth. The software may include a subprogram to assist inselecting the proper appliances for treatment of a particularmalocclusion at hand. Alternatively, the software may receive input fromthe practitioner for selection of the desired appliances 30. Once theappliances 30 have been selected and the desired ultimate locations ofthe appliances 30 on the patient's teeth has been determined, thesoftware determines the shape of the placement guides 26 and also thelocation of the placement guides 26 on the replica teeth 22.

Optionally, the software enables the practitioner, patient or otherobserver to see on a monitor or other video output a virtualrepresentation of the patient's teeth as they should appear at theconclusion of treatment using the selected appliances 30 when placed atcertain locations of the patient's teeth. Once the virtualrepresentation of the patient's teeth at the conclusion of treatment hasbeen observed, the software preferably enables the practitioner to makeadjustments in the locations of the appliances 30 on the replica teethor to select another appliance if desired. The software then makes anynecessary correction in the shape or location of the placement guides 26as needed. Optionally, input from the practitioner is provided in thepractitioner's office and transmitted to the manufacturing facility overthe internet.

An example of software for choosing appliances 30 is described inpending U.S. Patent Application Publication No. 2003/0163291, entitled“SELECTION OF ORTHODONTIC BRACKETS”. As an additional option, thesoftware includes subprograms for making custom orthodontic appliances30 using, for example, a computer numerical control milling machine,instead of selecting appliances 30 from an existing set of appliances.As an additional option, the software may select an orthodontic archwirefor subsequent placement in the slots of the appliances 30. This stepserves to further reduce the patient's time that is subsequently spentin the practitioner's chair.

The rapid prototyping machine (such as the Stratasys Dimension SSTapparatus described above) may also be used to form the placement guides26 on the dentition replica 20. In the embodiment shown in FIGS. 1-4,the placement guides 26 are formed using a soluble material while thedentition replica 20 is formed using a non-soluble material. An exampleof a suitable soluble material is WaterWorks brand material fromStratasys, Inc. An example of a suitable non-soluble material isacrylonitrile butadiene styrene (“ABS”).

A thin layer of release agent is then applied to the replica 20 andallowed to dry. An example of a suitable release agent is a watersoluble polyvinyl alcohol, such as “PA0810” from PTM & W Company ofSanta Fe Springs, Calif. Next, the practitioner or technician places anorthodontic appliance 30 in each receptacle 28. However, before theappliances 30 are placed in the receptacles 28, a quantity of acomposition 37 (FIG. 4) is placed between each appliance 30 and thecorresponding replica tooth 22.

Preferably, the composition 37 is a light-curable composition such as alight-curable adhesive, and the adhesive is coated across the base ofeach appliance 30. Preferably, the appliances 30 are adhesive precoatedappliances that have a layer of light-curable adhesive applied by themanufacturer to the base of each appliance 30. Such adhesive coatedappliances are described in U.S. Pat. Nos. 5,015,180, 5,172,809,5,354,199 and 5,429,299. The appliances 30 may be made of any suitablematerial such as metal (e.g., stainless steel), ceramic (e.g.,translucent polycrystalline alumina or monocrystalline alumina) orplastic (e.g., translucent polycarbonate).

If the appliances 30 are not precoated with adhesive in advance by theappliance manufacturer, the composition 37 is applied to the base ofeach appliance 30 immediately before placing the appliance 30 in thereceptacle 28. Suitable compositions 37 include orthodontic adhesivessuch as composites, compomers, glass ionomers and resin-modified glassionomers. Examples of light-curable adhesives include Transbond XT brandand Transbond LR brand adhesives from 3M Unitek Corporation. Examples ofchemical curing adhesives include Concise brand adhesive and Multi-Curebrand glass ionomer cement from 3M Unitek Corporation.

Next, firm pressure is applied to each appliance 30 in order to ensurethat the appliance 30 is firmly seated on the corresponding replicatooth 22. Preferably, finger pressure is applied directly to the facialside of the appliance 30 in order to seat the base of the appliance 30against the replica tooth surface. Excess adhesive is then removed.Since the placement guide 26 as illustrated in the drawings do notinclude an occlusal section, most of the excess adhesive is extrudedfrom beneath the base of the appliance 30 in an occlusal direction andtoward the outer tips of the replica teeth 22.

Subsequently, the composition 37 is allowed to harden. As one example,if the appliances 30 are made of metal or other opaque material and ifthe composition 37 is a light-curable adhesive, it is preferable toexpose the replica 20 to the curing light for a relatively long amountof time (such as 3 to 5 minutes) in order to ensure that the adhesivehas sufficiently hardened.

An example of a suitable curing light for hardening light-curableadhesive is a curing chamber such as the Triad 2000 brand visible curinglight system from Dentsply. Preferably, the curing chamber issufficiently large to contain a number of replicas 20 so that thecomposition 37 on a number of replicas 20 can be cured simultaneously.In such a chamber, the light source and the replicas 20 preferably moverelative to each other during energization of the light source tofacilitate curing of each portion of the composition 37. As analternative to the light curing chamber, a hand-held curing unit may beused, such as Ortholux XT brand curing unit from 3M Unitek Corporation.

As an additional option, the replica 20 including the replica teeth 22may be made from a material that transmits actinic radiation. Suitablematerials include epoxy resins that are transparent or translucent whenhardened. Preferably, the material is optically clear. An example of asuitable epoxy is E-CAST F-82 clear epoxy resin and No. 302 (or UCE-302)hardener, from United Resin Corporation. Other suitable materialsinclude polyesters and urethanes. The use of transparent or translucentmaterials is advantageous in instances where the appliances 30 are madeof opaque materials, since the actinic radiation can be transmittedthrough the replica 20 for curing portions of the adhesive that arelocated adjacent the middle of the appliance base. Actinic radiation caninclude wavelengths in the visible range, ultraviolet range, infraredrange or any combination thereof, in accordance with the type ofphotoinitiator contained in the adhesive.

Subsequently, the placement guides 26 are removed from the dentitionreplica 20 and the appliances 30. During this step, the appliances 30remain bonded to the replica teeth 22. In this embodiment, the placementguides 26 are made of a soluble material and the replica 20 is made ofan insoluble material. The placement guides 26 are removed by soakingthe replica 20 and the placement guides 26 in water such that theplacement guides 26 are dissolved or at least partially dissolved.

Next, and as shown in FIG. 5, a spacer material 35 is applied to thereplica 20. The spacer material 35 preferably comprises a custom-formedmaterial. As an example, the spacer material 35 may be dental impressionputty that is pressed into place and formed by hand. An example of asuitable impression putty is “Express STD” brand impression putty from3M Espe.

Preferably, the spacer material 35 extends over at least a majority ofthe facial surface area, the occlusal surface area and the lingualsurface area of the replica teeth 22. However, the spacer material 35may be omitted from contacting certain surfaces of the replica teeth 22if desired, such as the lingual surface area of the replica teeth 22. Inthe illustrated embodiment, the spacer material 35 extends over thereplica gingival tissue 24 as well as lingual areas of the replicateeth. Preferably, and as shown in FIG. 5, the spacer material 35 isthicker in regions located gingivally of the appliances 30 in comparisonto remaining regions of the spacer material 35.

As another alternative, the spacer material 35 is formed using a rapidprototyping method. Examples of suitable rapid prototyping methodsinclude stereolithography, thermojet printing and the like. Preferably,the digital data described above representing the shape of a portion ofthe patient's dental arch is used in the rapid prototyping method tomake the spacer material 35.

Additionally, the spacer material 35 can be any one of a number ofmaterials other than dental putty, such as a thermoset material. Anexample of an alternative material is a silicone material, such as “RTV615” from General Electric. Other suitable materials include, forexample, materials used in rapid prototyping processes, such asthermoplastics (including nylons), thermoplastic elastomers andcomposites (e.g., glass-filled nylons). Examples of such materialsinclude “Sinterstation HiQ Series SLS System” brand materials (includingDuraForm brand PA polyamide nylon, DuraForm Brand GF glass-filled nylon,and Somos brand 201 materials), “Viper SLA” brand materials from 3DSystems (including Dreve Otoplatik Fototec brand SL materials and Accurabrand SL materials), and “Thermojet” brand materials (includingThermojet brand 88 and Thermojet brand 2000 materials).

Optionally, the spacer material 35 may be temporarily held in place onthe replica 20 by use of an adhesive, such as a pressure sensitiveadhesive. If the spacer material 35 is preformed, it preferably has theshape of the underlying replica dental arch when the spacer material 35is relaxed. Alternatively, the spacer material 35 is formed to match theshape of the replica dental arch 20 when it is applied to the latter.Optionally, the spacer material 35 is coated with a layer of pressuresensitive adhesive on one side and initially connected to a sheet ofrelease material until such time as it is needed for use.

Subsequently, a shell 38 is formed over the spacer material 35 asillustrated in FIG. 6. Preferably, the shell 38 is shaped by vacuumforming a sheet of material over the sheet of spacer material 35. Asuitable material for the shell 38 is a sheet of polycarbonate such asMakrolon brand material from Bayer or Lexan brand polycarbonate from GEhaving a thickness of 0.06 inch. Other materials, such aspolyethyleneterephthalate glycol (“PETG”) may also be used. Heat isapplied during the vacuum forming process in order to facilitateconformance of the sheet to the external configuration of the spacermaterial 35.

Once the shell 38 has hardened, the shell 38 is detached from the spacermaterial 35. The spacer material 35 is then detached from the replica 20and the appliances 30 and set aside or discarded. During detachment ofthe spacer material 35 from the replica 20, the appliances 30 remainbonded to the replica teeth 22.

Excess portions of the shell 38 are then trimmed as desired. Next, stopmembers 39 (FIG. 7) are formed to facilitate subsequent positioning ofthe tray relative to the patient's teeth during a bonding procedure. Thestop members 39 may be made by placing curable material on the replica20 or alternatively within the channel of the shell 38. Preferably, onceconstruction of the tray has been completed, the stop members 39 arelocated along the curved longitudinal axis of the tray channel and nextto the bottom wall portion of the tray that defines the channel.

In the embodiment illustrated in FIG. 7, three spaced-apart stop members39 are made by placing curable material across occlusal sections of thereplica dental arch 20. One stop member 39 is formed near the center ofthe replica dental arch 20, while the other two stop members 39 areformed near the right end and left end respectively of the replicadental arch 20. However, other constructions are possible. For example,a single stop member 39 may be provided that extends along a substantialmajority of the curved longitudinal axis of the replica dental arch 20.Alternatively, two stop members 39 may be provided, each of whichextends along a majority of the left quadrant and the right quadrantrespectively of the replica dental arch 20 and follows the curvedlongitudinal axis of the arch.

Additionally, or as an alternative to occlusal stop members, one or morestop members 39 may be provided along the lingual surfaces and/or thefacial surfaces of the replica dental arch 20. Lingual and facial stopmembers may be particularly advantageous to ensuring proper fitting andplacement of the tray in instances when the patient's maloccluded teethpresent diverging tooth angulations.

The stop members 39 may be made from a variety of materials. Suitablematerials include, for example, an orthodontic or dental adhesive, adental restorative material, or a bite registration material. An exampleof a suitable bite registration material is “Imprint” bite registrationmaterial from 3M Espe. Preferably, the stop members 39 are made of athermosetting material that, after hardening, does not substantiallysoften upon contact with heat. Preferably, the stop members 39 transmitactinic radiation and retain their shape over extended periods of time.

Next, the shell 38 is placed over the replica dental arch 20 includingthe unhardened stop members 39. The shell 38 is pressed toward thereplica arch 20 with sufficient force to deform the shape of theunhardened stop members 39 and bring the shell 38 to a desired positionrelative to the replica 20 as the stop members 39 are flattened. Thisdesired position is somewhat adjacent the replica 20, but issufficiently spaced from the replica 20 so that a quantity of matrixmaterial may be received between the shell 38 and the replica 20 asdescribed below. The stop members 39 are then allowed to harden. Oncehardened, the stop members 39 have a gingival or tooth-facing surfacethat matches the occlusal surface of the facing occlusal section of thereplica tooth or teeth 22.

A matrix material 40 is then applied, either to the replica 20 or to thechannel of the shell 38. For example, if the matrix material 40 isrelatively viscous and resembles a semi-liquid or gel, the matrixmaterial 40 may be applied to the replica 20 as the replica 20 appearsin FIG. 7, using a syringe, brush or other technique. The matrixmaterial 40 is not shown in FIG. 7.

Alternatively, if the matrix material has a relatively low viscosity andresembles a liquid, it may be preferable to invert the shell 38 suchthat the open side of the channel of the shell 38 is facing upwardly asshown in FIG. 8. If the shell 38 is inverted, the shell 38 is notinitially trimmed along the outermost distal sides (corresponding to theends of the dental arch) so that the liquid matrix material 40 iscontained within the shell channel.

Subsequently, the replica 20 is positioned in the shell 38 such that thematrix material 40 is received in the channel of the shell 38 andbetween the shell 38 and the replica 20. As shown in FIG. 8, the matrixmaterial 40 surrounds the appliance 30 and also extends along the labialand lingual surfaces of the replica tooth 22. Moreover, the matrixmaterial 40 extends along the bottom and side wall surfaces of the shell38. The stop members 39 serve to properly position the shell 38 from theexternal surfaces of the replica teeth 22 as the matrix material 40 isreceived in the shell channel. The matrix material 40 is then allowed toharden.

Preferably, the matrix material 40 surrounds each appliance 30 and theentire replica arch 20 except in areas near the stop members 39, whichremain in contact with the occlusal sections of the replica 20.Preferably, the matrix material 40 and the stop members 39 chemicallybond to each other as the matrix material 40 has hardened, so that thestop members 39 are not unintentionally detached during the subsequentsteps.

Preferably, the matrix material 40 has a relatively low viscosity beforehardening so that intimate contact between the matrix material 40 andeach appliance 30 is assured. In this manner, the matrix material 40 isable to substantially penetrate in various recesses, cavities and otherstructural features of each appliance 30 so that a secure connectionbetween the appliance 30 and the matrix material 40 can be established.An example of a suitable matrix material having a relatively lowviscosity is a silicone material such as “RTV615” silicone material fromGeneral Electric as mentioned above. The relatively low viscosity ofthis silicone material also assures that this material will assume aconfiguration that closely matches the shape of the adjacent surfaces ofthe replica teeth 22.

Alternatively, the matrix material 40 may comprise a dental impressionmaterial or a bite registration material. Suitable materials includepolyvinylsiloxane impression material, such as Memosil 2 brand vinylpolysiloxane material from Heraeus Kulzer Inc., or Peppermint Snap brandclear bite registration material from Discus Dental. If a light-curableadhesive is to be subsequently used for bonding the appliances 30 to thepatient's teeth, the matrix material 40 is preferably optically clearand transmits actinic radiation without substantial absorption.

Once the matrix material 40 has hardened, the shell 38, together withthe matrix material 40 and the appliances 30, are detached from thereplica 20. The use of the release agent as mentioned above helpsfacilitate detaching of the appliances 30 from the corresponding replicateeth 22. Excess material of the shell 38 and excess matrix material 40are then trimmed as desired as discarded. The resultant tray (comprisingthe shell 38, the matrix material 40 and the stop members 39) is shownin cross-sectional view in FIG. 9 and is designated by the numeral 44.

Once the patient has returned to the office, the patient's teeth thatare to receive appliances 30 are isolated using cheek retractors, tongueguards, cotton rolls, dry angles and/or other articles as needed. Theteeth are then thoroughly dried using pressurized air from an airsyringe. Etching solution (such as 3M Unitek Transbond XT brand etchinggel) is then dabbed onto the teeth in the general area that is to becovered by the appliances 30, taking care to prevent the etchingsolution from flowing into interproximal contacts or engaging the skinor gingiva.

After the etching solution has remained on the selected tooth surfacesfor a period of approximately thirty seconds, the solution is rinsedaway from the teeth with a stream of water for fifteen seconds. Thepatient's teeth are then dried by the application of pressurized airfrom an air syringe (for example, for a time period of thirty seconds)and excess water is removed by suction. Care should also be undertakento ensure that the saliva does not come in contact with the etchedenamel surfaces. Cotton rolls and other absorbent devices are replacedas needed, again making sure that saliva does not contact the etchedenamel. Air from the air syringe may then be applied to the teeth againto ensure that the teeth are thoroughly dried.

Next, a bonding adhesive is applied to the hardened composition 37and/or the selected areas of the patient's teeth. Optionally, theadhesive is a two-component adhesive as depicted in FIG. 9. For example,the first component 41 is a Transbond brand XT primer, and the secondcomponent 43 is Transbond brand Plus self-etching primer, both from 3MUnitek. The first component 41 is applied to the hardened composition 37and the second component 43 is applied to the area of the patient'stooth that is to receive the appliance 30. In FIG. 9, the patient'stooth is designated by the numeral 42.

After the first component 41 has been applied to the hardenedcomposition 37 and the second component 43 has been applied to thecorresponding area of the patient's tooth 42, the tray 44 is thenpositioned over the corresponding teeth and seated, optionally with aswinging, hinge-type motion. Since the shape of the cavity of the matrixmaterial 40 and the stop members 39 together match the shape of theunderlying teeth, the appliances 30 are simultaneously seated againstthe underlying teeth 42 at precisely the same locations corresponding tothe previous position of the appliances 30 on the replica 20.

Preferably, the tray 44 has a shape and stiffness that is sufficient topress the appliances 30 against the teeth 42 as the adhesive cureswithout the application of external pressure. However, as an option,external pressure may also be applied to the occlusal and facialsurfaces of the tray 44 until such time as the bonding adhesive hassufficiently hardened. For example, finger pressure may be used tofirmly press the appliances 30 against the enamel surfaces of thepatient's teeth 42.

Other examples of suitable two-component chemical curing adhesivesinclude Sondhi brand Rapid-Set indirect bonding adhesive, Unite brandadhesive and Concise brand adhesive, all from 3M Unitek. Alternatively,a resin-modified glass ionomer cement may be employed.

Once the bonding adhesive has hardened, the tray 44 is carefully removedfrom the patient's dental arch. Preferably, the shell 38 is firstseparated from the matrix material 40, which remains in place over thedental arch along with the appliances 30. Next, the matrix material 40is detached from the appliances 30. Optionally, a hand instrument suchas a scaler may be used to help hold each appliance 30 against thesurface of the respective tooth 42 of the patient as the matrix material40 is peeled away from the appliances 30. However, in instances where arelatively soft matrix material is employed or otherwise readilyreleases from the appliances 30, the use of a scaler to help avoidfracturing the fresh adhesive bond is optional.

As another option, the shell 38 may be separated from the matrixmaterial 40 before the bonding adhesive has hardened. This option isparticularly useful when the bonding adhesive is a light-curableadhesive.

Once the matrix material 40 has been detached from the appliances 30, anarchwire is placed in the slots of the appliances 30 and ligated inplace. Suitable ligation devices include tiny, elastic O-rings as wellas sections of wire that are tied in a loop around the appliances 30. Asanother option, the appliances 30 may be self-ligating appliances thatinclude a latch for releasably engaging the archwire such as thosedescribed in U.S. Pat. No. 6,302,688 and PCT Publication No.WO02/089693.

The hardened composition 37 provides a contoured bonding surface for thebase of the corresponding appliance 30. The configuration of thisbonding surface closely matches the shape of the patient's tooth surfaceand consequently facilitates the subsequent bond (using the bondingadhesive components 41, 43) that is established between the appliance 30and the tooth 42. The custom bonding surface reduces the likelihood thatthe appliances 30 will become unintentionally detached from thepatient's teeth during the course of treatment.

The use of the spacer material 35 in combination with the stop members39 in the method described above helps to provide an appropriate regionfor receiving matrix material 40 in the shell 38. The spacer material 35and the stop members 39 can be shaped as needed to provide precisely thevolume and configuration of region as may be desired. For example, thespacer material 35 and the stop members 39 may help ensure that auniform thickness of matrix material is subsequently provided around thesubstantial extent of the tooth 42 with the exception of the areasadjacent the appliance 30 and the occlusal section of the dental archadjacent the stop members 39.

Moreover, the use of the spacer material 35 facilitates the use of amatrix material 40 having a relatively low viscosity, such as a matrixmaterial having a liquid consistency. The shell 38 is relatively stiff,and consequently maintains its shape during forming and hardening of thematrix material 40. The tray 44 is constructed such that the shell 38(other than the stop members 39) does not directly contact the patient'steeth or gingival tissue. Instead, only the matrix material 40 and thestop members 39 come into contact with the patient's teeth.

Advantageously, the relatively soft matrix material 40 is flexible andcan accommodate a limited amount of tooth movement. For example, theteeth 42 of the patient may have slightly shifted between the time thatthe impressions are taken and the time that the tray 44 is fitted in thepatient's oral cavity for bonding the appliances 30. The matrix material40 has sufficient flexibility to comply with small shifts or adjustmentsin the patient's tooth positions, so that the appliances 30 are properlybonded to the intended, pre-determined locations on the patient's teeth42.

The matrix material 40 preferably has a viscosity before curing that isless than about 60,000 cp. More preferably, the matrix material 40 has aviscosity before curing that is less than about 25,000 cp. Mostpreferably, the matrix material 40 has a viscosity before curing that isless than about 8000 cp. Once hardened, the matrix material 40 has aShore A hardness that is in the range of about 10 to about 80, morepreferably in the range of about 30 to about 60 and most preferably inthe range of about 40 to about 50.

The stop members 39 are relatively inflexible and have a Shore Ahardness that is greater than the Shore A hardness of the matrixmaterial 40. Preferably, the stop members 39 have a Shore A hardnessthat is greater than about 60 and more preferably is greater than about90.

The placement guides 26 are a significant advantage, in that time andeffort associated careful, manual positioning of the appliances 30 onthe replica 20 can be avoided. Moreover, when constructed usingautomated techniques as described above, the placement guides 26 help toavoid manual errors in positioning of the appliances 30. As anadditional advantage, the matching shape of the placement guides 26 andthe corresponding bases of the selected appliances 30 provides assurancethat the correct appliance 30 has been placed on the proper replicatooth 22.

FIG. 10 is a view somewhat similar to FIG. 4, except illustrating aplacement guide 26 a that has been constructed in accordance with analternative embodiment of the invention. In this embodiment, theplacement guide 26 a is made of the same material as the material of thedentition replica 20 a including the teeth replicas 22 a, and thedentition replica 20 a and the placement guides 26 a form an integral,unitary body. As one example, a stereolithography machine maybe used toprint out the dentition model 20 a and the placement guides 26 atogether.

The placement guides 26 a, like the placement guides 26, includesections such as a mesial section, a distal section and a gingivalsection 34 a. Only the gingival section 34 a is shown in FIG. 10.Optionally, at least part of an occlusal section (not shown) is alsoprovided. Each of the sections is detached from the adjacent replicatooth 22 a once the appliance 30 a is bonded to the replica toothsurface.

In the embodiment illustrated in FIG. 10, the mesial, gingival anddistal sections of the placement guides 26 a include a weakened portion27 a that comprises a relatively thin web of material. This web ofmaterial is sufficiently thin to enable the sections to be broken awayfrom the replica tooth surface once the adjacent appliance 30 a isbonded in place. For example, the weakened portions 27 a may be made ofa relatively brittle material that fractures when bent by thepractitioner to remove the sections. As another alternative, theweakened portions 27 a are sufficiently thin to be readily cut by aknife in order to detach the sections from the adjacent replica tooth 22a. In other respects, the placement guide 26 a is substantially the sameas the placement guides 26 described above.

A variety of other embodiments and alternative constructions are alsopossible. For example, additional constructions of the stop members aredescribed in pending U.S. Patent Application entitled “METHOD OF MAKINGINDIRECT BONDING APPARATUS FOR ORTHODONTIC THERAPY”, Ser. No. ______[attorney docket no. 60729US002], filed Apr. 4, 2005. Additionally,before the tray is shipped to the practitioner, a bonding compositionmay be applied to the base of each appliance 30, 30 a by themanufacturer and then packaged in a container as described in pendingU.S. patent application Ser. No. 10/678,286 entitled “APPARATUS FORINDIRECT BONDING OF ORTHODONTIC APPLIANCES AND METHOD OF MAKING THESAME”. Additionally, the bonding composition of at least one appliancemay differ from the bonding composition of at least one other appliance30, 30 a in the tray in terms of composition, properties orcharacteristics, as described in pending U.S. patent application Ser.No. 10/742,561, entitled “PACKAGED ORTHODONTIC ASSEMBLY WITH ADHESIVEPRECOATED APPLIANCES”, such that the bonding composition can be tailoredto enhance the bond between the particular selected appliance 30,30 aand its intended tooth 42. Further, an archwire selected by software asdescribed above can be placed in the slots of the appliances 30, 30 abefore the matrix material 40 is applied to the shell 38, as analternative to placing the archwire in the slots after the tray has beenremoved.

As an additional option, the tray 44 may include only a single layer,instead of the two layers (comprising the matrix material 40 and theshell 38) as described above. Furthermore, the placement guides may beconstructed with wall sections having a relatively small height in afacial-lingual direction, such that the placement guides need not beremoved from the dentition replica and can instead remain in placeduring construction of the tray.

Additionally, the tray 44 as described above may be used for bondingonly a single appliance 30, 30 a to a patient's tooth. For example, aportion of the tray 44 described above may be used to bond a singleappliance to a single tooth subsequent to the time that other appliancesare bonded, such as in instances where access to the tooth is initiallyhindered by other teeth. As another example, a portion of the tray 44described above may be used to rebond an appliance that hasunintentionally debonded from the tooth, or to bond a new appliance to atooth to replace the original appliance.

All patents, patent applications and other publications identifiedherein are expressly incorporated by reference into this disclosure.Moreover, a number of other variations, modifications and additions arealso possible without departing from the spirit of the invention.Accordingly, the invention should not be deemed limited to the specificembodiments described in detail above, but instead only by a fair scopeof the claims that follow and their equivalents.

1. A method of making an indirect bonding tray for orthodontic treatmentcomprising: providing a replica of a patient's dentition, wherein thereplica includes replica tooth structure; providing a guide on thereplica tooth structure at a location corresponding to the intendedlocation of an orthodontic appliance on the patient's tooth structure;placing an orthodontic appliance on the replica tooth structure next tothe guide; and forming a tray over the replica including the orthodonticappliance.
 2. A method of making an indirect bonding tray fororthodontic treatment according to claim 1 and including the act ofremoving the guide from the replica tooth structure after the act ofplacing the orthodontic appliance on the replica tooth structure.
 3. Amethod of making an indirect bonding tray for orthodontic treatmentaccording to claim 2 wherein the act of removing the guide includes theact of dissolving at least part of the guide.
 4. A method of making anindirect bonding tray for orthodontic treatment according to claim 2wherein the act of removing the guide includes the act of detaching atleast part of the guide.
 5. A method of making an indirect bonding trayfor orthodontic treatment according to claim 2 wherein the act ofremoving the guide is carried out before the act of forming a tray overthe replica.
 6. A method of making an indirect bonding tray fororthodontic treatment according to claim 1 wherein the act of providingthe replica and the act of providing the guide are carried out by makingan integral, unitary body.
 7. A method of making an indirect bondingtray for orthodontic treatment according to claim 6 wherein the act ofmaking an integral, unitary body is carried out at least in part using arapid prototyping method.
 8. A method of making an indirect bonding trayfor orthodontic treatment according to claim 1 wherein the act ofproviding a replica includes the act of forming a replica, and whereinthe act of providing a guide includes the act of applying a material tothe replica after the replica has been formed.
 9. A method of making anindirect bonding tray for orthodontic treatment according to claim 8wherein the act of forming a replica and the act of applying a materialto the replica after the replica has been formed are carried out atleast in part using a rapid prototyping process.
 10. A method of makingan indirect bonding tray for orthodontic treatment according to claim 8wherein the act of applying a material to the replica includes the actof applying a soluble material to the replica.
 11. A method of making anindirect bonding tray for orthodontic treatment according to claim 1wherein the act of providing a guide includes the act of providing atleast three wall sections for engagement with three sides of a base ofthe appliance.
 12. A method of making an indirect bonding tray fororthodontic treatment according to claim 1 wherein the act of providinga guide includes the act of providing a guide with a receptacle forreceiving a base of the appliance.
 13. A method of making an indirectbonding tray for orthodontic treatment according to claim 12 wherein thereceptacle has a shape that is complemental to the shape of at leastthree sides of the base.
 14. A method of making an indirect bonding trayfor orthodontic treatment according to claim 1 wherein the act ofplacing an orthodontic appliance on the replica tooth structure includesthe act of applying a curable material to a region between theorthodontic appliance and the replica tooth structure.
 15. A method ofmaking an indirect bonding tray for orthodontic treatment according toclaim 14 wherein the curable material is a light-curable material.
 16. Amethod of making an indirect bonding tray for orthodontic treatmentaccording to claim 1 wherein the replica of the patient's dentitionincludes a number of replica teeth, and including the act of providing anumber of guides each corresponding to one of the teeth and the act ofproviding a number of appliances each corresponding to one of theguides.
 17. An assembly for making an indirect bonding tray fororthodontic treatment comprising: a dentition replica including a numberof replica teeth; a number of guides each connected to a correspondingtooth of the dentition replica, wherein each guide includes areceptacle; and a number of orthodontic appliances each received in acorresponding receptacle.
 18. An assembly for making an indirect bondingtray for orthodontic treatment according to claim 17 wherein at leastpart of the guides are detachably connected to the dentition replica.19. An assembly for making an indirect bonding tray for orthodontictreatment according to claim 17 wherein at least part of at least oneguide is made of a soluble material.
 20. An assembly for making anindirect bonding tray for orthodontic treatment according to claim 17wherein at least some of the guides include a weakened section fordetaching the guides from the dentition replica.
 21. An assembly formaking an indirect bonding tray for orthodontic treatment according toclaim 17 wherein the receptacles have a shape that is complemental inconfiguration to at least a portion of the corresponding appliance. 22.An assembly for making an indirect bonding tray for orthodontictreatment according to claim 17 wherein the appliances each have a base,and wherein the guides each include wall sections extending along thebase.
 23. An assembly for making an indirect bonding tray fororthodontic treatment according to claim 22 wherein the wall sections donot completely surround the base of the corresponding appliances.